This is the 5.4.145 stable release

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Merge 5.4.145 into android11-5.4-lts

Changes in 5.4.145
	ext4: fix race writing to an inline_data file while its xattrs are changing
	fscrypt: add fscrypt_symlink_getattr() for computing st_size
	ext4: report correct st_size for encrypted symlinks
	f2fs: report correct st_size for encrypted symlinks
	ubifs: report correct st_size for encrypted symlinks
	kthread: Fix PF_KTHREAD vs to_kthread() race
	xtensa: fix kconfig unmet dependency warning for HAVE_FUTEX_CMPXCHG
	gpu: ipu-v3: Fix i.MX IPU-v3 offset calculations for (semi)planar U/V formats
	reset: reset-zynqmp: Fixed the argument data type
	qed: Fix the VF msix vectors flow
	net: macb: Add a NULL check on desc_ptp
	qede: Fix memset corruption
	perf/x86/intel/pt: Fix mask of num_address_ranges
	perf/x86/amd/ibs: Work around erratum #1197
	perf/x86/amd/power: Assign pmu.module
	cryptoloop: add a deprecation warning
	ARM: 8918/2: only build return_address() if needed
	ALSA: hda/realtek: Workaround for conflicting SSID on ASUS ROG Strix G17
	ALSA: pcm: fix divide error in snd_pcm_lib_ioctl
	ARC: wireup clone3 syscall
	media: stkwebcam: fix memory leak in stk_camera_probe
	igmp: Add ip_mc_list lock in ip_check_mc_rcu
	USB: serial: mos7720: improve OOM-handling in read_mos_reg()
	ipv4/icmp: l3mdev: Perform icmp error route lookup on source device routing table (v2)
	powerpc/boot: Delete unneeded .globl _zimage_start
	net: ll_temac: Remove left-over debug message
	mm/page_alloc: speed up the iteration of max_order
	Revert "r8169: avoid link-up interrupt issue on RTL8106e if user enables ASPM"
	x86/events/amd/iommu: Fix invalid Perf result due to IOMMU PMC power-gating
	Revert "btrfs: compression: don't try to compress if we don't have enough pages"
	ALSA: usb-audio: Add registration quirk for JBL Quantum 800
	usb: host: xhci-rcar: Don't reload firmware after the completion
	usb: mtu3: use @mult for HS isoc or intr
	usb: mtu3: fix the wrong HS mult value
	xhci: fix unsafe memory usage in xhci tracing
	x86/reboot: Limit Dell Optiplex 990 quirk to early BIOS versions
	PCI: Call Max Payload Size-related fixup quirks early
	Linux 5.4.145

Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: Ic5a02a653d255a9bf1729e728011425e45e293aa

kernel/kthread.c

@@ -77,6 +77,25 @@ static inline struct kthread *to_kthread(struct task_struct *k)
 	return (__force void *)k->set_child_tid;
 }
 
+/*
+ * Variant of to_kthread() that doesn't assume @p is a kthread.
+ *
+ * Per construction; when:
+ *
+ *   (p->flags & PF_KTHREAD) && p->set_child_tid
+ *
+ * the task is both a kthread and struct kthread is persistent. However
+ * PF_KTHREAD on it's own is not, kernel_thread() can exec() (See umh.c and
+ * begin_new_exec()).
+ */
+static inline struct kthread *__to_kthread(struct task_struct *p)
+{
+	void *kthread = (__force void *)p->set_child_tid;
+	if (kthread && !(p->flags & PF_KTHREAD))
+		kthread = NULL;
+	return kthread;
+}
+
 void free_kthread_struct(struct task_struct *k)
 {
 	struct kthread *kthread;
@@ -177,10 +196,11 @@ void *kthread_data(struct task_struct *task)
  */
 void *kthread_probe_data(struct task_struct *task)
 {
-	struct kthread *kthread = to_kthread(task);
+	struct kthread *kthread = __to_kthread(task);
 	void *data = NULL;
 
-	probe_kernel_read(&data, &kthread->data, sizeof(data));
+	if (kthread)
+		probe_kernel_read(&data, &kthread->data, sizeof(data));
 	return data;
 }
 
@@ -491,9 +511,9 @@ void kthread_set_per_cpu(struct task_struct *k, int cpu)
 	set_bit(KTHREAD_IS_PER_CPU, &kthread->flags);
 }
 
-bool kthread_is_per_cpu(struct task_struct *k)
+bool kthread_is_per_cpu(struct task_struct *p)
 {
-	struct kthread *kthread = to_kthread(k);
+	struct kthread *kthread = __to_kthread(p);
 	if (!kthread)
 		return false;
 
@@ -1296,11 +1316,9 @@ EXPORT_SYMBOL(kthread_destroy_worker);
  */
 void kthread_associate_blkcg(struct cgroup_subsys_state *css)
 {
-	struct kthread *kthread;
+	struct kthread *kthread = __to_kthread(current);
+
 
-	if (!(current->flags & PF_KTHREAD))
-		return;
-	kthread = to_kthread(current);
 	if (!kthread)
 		return;
 
@@ -1322,13 +1340,10 @@ EXPORT_SYMBOL(kthread_associate_blkcg);
  */
 struct cgroup_subsys_state *kthread_blkcg(void)
 {
-	struct kthread *kthread;
+	struct kthread *kthread = __to_kthread(current);
 
-	if (current->flags & PF_KTHREAD) {
-		kthread = to_kthread(current);
-		if (kthread)
-			return kthread->blkcg_css;
-	}
+	if (kthread)
+		return kthread->blkcg_css;
 	return NULL;
 }
 EXPORT_SYMBOL(kthread_blkcg);